Translating device



Aug. w, 1943. B. B. BAUER 2,32%,0

TRANSLATING DEVICE Filed May 21, 1941 Z2 37 @3 f7 0 52 fl! j? 1% 5f,cyeafifi jag Q02 )2 ja f @mmw manual adjustments areto Patented Aug. 10,1943 TRANSLATING DEVICE Benjamin B. Bauer, Chicago, 111., 'assignor toS. N.

Shure and Frances Shure,

ness as Shure Brothers,

Application May 21, 1941, Serial No. 394,564 Claims. (Cl. 179-10041)This invention relates to phonograph translating devices having atorsional drive rod. The invention is applicable to either a recorder orreproducer and certain features of the invention are of generalapplication to a torsion rod drive. An important feature howeverconcerns itself with the use of a relatively stiff translating means perse in connection with a torsion drive rOd.

A torsion drive rod for lateral record grooves utilizes a needle orstylus extending generally" transversely to the rod axis. In such aconstruction, it is desirable from a theoretical angle to endow thedrive rod with only one degree of movement; i. e. torsional about itslongitudinal axis. Longitudinal and lateral rod movement are ordinarilyto be avoided.

As is well known, the width of a laterally cut groove is constantlyvarying. Where the groove width decreases, a vertical component of forceis created tending to raise the needle, assuming the needle is above ahorizontal record. This is known as the pinch effect and should beconsidered as a substantial factor. In practice therefore, it is highlydesirable to provide for some transverse rod travel in a directionperpendicular to the record under normal operating conditions.

It follows that there should be a controlled elasticity for needlemovements tending to vibrate the drive rod perpendicularly to therecord. Since the rotational elasticity of the drive rod is highlyimportant in regard to characteristic control, it is clear that thesetwo elasticities should preferably be independent. This has notheretofore been true of prior devices. In general the mechanicalconstruction interlinked these two elasticities so that independentcontrol of each was impossible. As a rule, the final characteristicswere a compromise between conflicting tendencies.

In a torsion drive device, there must be some physical means forconnecting the drive rod with the translator per se; i. e. with theelement where energy conversion takes place. If a translator has agreater stifiness than is desirable to project to the needle point, acoupling must be used so that the needle may be deflected more easily.

As is well known, the moment of inertia of a rotary part is a functionof the square of the radius. By keeping down the radius to a minimumvalue the moment of inertia is reduced. However, mechanical couplingdetails require relatively larger and smaller parts, particularly if eprovided. In such case, I dispose the smaller its in the drive rod seenin Figs. 3 and 4, the-vertical dimension is trustee, doing busiapartnership part of the system and have the larger parts in two, a.flexible coupling maybe provided which functions to change largevibrations of a flexible .element to smaller vibrations of a stillerelement.

Referring now to the drawing:

Figure 1 is a top plan view of a translating device, with the top casingmember removed;

Fig. 2 is a section on 22 of Fig. 1 but with the top casing member inplace;

Fig. 3 is a front elevation of a translating device;

Fig. 4-is' an enlarged view of'the torsion rod bearing shown in Fig. 3;1

Fig. 5 is an enlarged view of a modified torsion rod bearing;

Fig. 6 is a sectional elevation of a modified translator and clampcombined; and

Fig. 7 is a section on 1-4 of Fig. 6.

The translating device as a whole includes a pair of complementary casemembers In and H. Both members are generally similar and may be ofstamped aluminum, sheet iron, die cast or may even be of a suitableplastic material. Both base members are generally dished to provide acomparatively large compartment I2 formed by wall portions l3 and 14.Rear edges l5 and I6 of the case may be inturned and fitted against aninsulating terminal block [1.

The front portion of the case is shaped to provi-de a pair of journalsl8 and IS, the metal being pushed inwardly to form the journals. Thefree I, edges 20 and 2| of the two casing shells meet along the casesides and front. The two shells may be maintained tightly in position bybolts passing through apertures 22, 23 and 24.

Journal l8 and preferably also journal I9 are not circular, as might beexpected but have an elongated shape with the long dimension beingperpendicular to the general casing plane. As

somewhat longer than the horizontal one. The diiference need not begreat and in practice need only amount to about a hundredth of an inchor so. The drawing obviously shows the elongation exaggerated.

Disposed within the forepart of the casing is a torsion drive rod2G.having a generally circular section and a male coupling element as aflat tail piece 21. Drive rod 26 may have an axial threaded channel 28into which a thumb screw 29 may be disposed. A generally transverseneedle receiving slot 30 is provided at an intermedate part of the rodand into this may be disposed a needle 3|. This needle may be either aconventional reproducing needle or a jewel or may be a cutting stylusfor recording. The needle is clamped by screw 29 and preferably extendsforward of the device, as shown in Fig. 2. A suitable aperture 32 incasing member II is provided for clearing the needle. A tubular guard 33is carried by easing member and extends around needle 3| for a distanceso that only the tip of the needle clears. Thus guard 33 will take upany shock above that necessary to push the needle tip Rod 26 has reducedcircular bearing portions 34 and 35 on opposite sides of the needleclamping region and these reduced portions register with journals l8 andI9 respectively. Around reduced portions 34 and 35 are flexible sleeves36 and 31 of rubber, felt or the like. It will be noted that the casingflares outwardly on both sides of journal l9. Preferably, reducedportion 35 has about the same length as bearing journal l9 while sleeve31- is longer than reduced portion 35. Thus the sleeve materialstretches out on both ends of the bearing portion and efiectively formsa thrust bearing for axially directed forces. The ends of the sleevesare thus firmly retained against longitudinal force. A somewhat similarthrust bearing action may be obtained by sleeve 36 on reduced portion34.

Both sleeves 36 and 31 are just thick enough so that a resilient bearingis provided. Each sleeve is originally uniform in thickness so that anincrease in resiliency along a vertical axis, as seen in Figs. 3 and 4,results. The elongation of one or both bearing journals may besufficient to provide open regions 36 and 39 above and below thesleeves. It is understood that substantially the same result may beobtained by varyin the sleeve thickness and having round bearing. or byhaving uniform sleeves in round journals and flattening the drive rod atthe top and bottom as shown in Fig. for example. The thickest part ofthe variable sleeve would be at the horizontal axis and this would bemost compressed.

Since the compression of the sleeves 36 and 31 controls the torsionalflexibility of the drive rod, it is clear that this characteristic isindependent of the vertical elasticity of the drive rod mounting. Theangular extent and depth of free bearing regions 38 and 39 willdetermine the elasticity of the rod mounting to vertically transverseforces. Hence the elastic properties of the drive rod mounting totorsional movement and vertical translation may be independentlycontrolled.

' Tail piece 21 may have disposed on opposite sides thereof fiat rubberor other flexible pads 40 and 4|. If desired one pad may be omitted. Itis preferred however to have one pad of different compressibility andresistance than the other. Flexible materials like rubber, leather, corkor the like have a non-linear characteristic of stress and strain, thecompressibility and resistance depending upon the initial compression.It is clear that by having pads 40 and 4| difierent, it is possible tocontrol the vibratory characteristics of the entire coupling. Thusparticularly desirable results have been secured by having one pad of amaterial whose predominant characteristic is elasticity, such as liverubber, and by having the other pad of viscous material whosepredominant characteristic is resistance, such as viscoloid.

A pair of clamping members 42 and 43 engage the padded tail piece andthe pressure of engagement may be controlled by bolt 44 loosely passingthrough one piece, here 42, and threadedly engaging the other piece. Ineffect, the couplin consists generaly of a male member on the drive rodand a female member cooperating therewith.

As shown in Fig. l, clamping members 42 and 43 are generally T-shapedwith the bottom of the T preferably engaging the tail piece 21. Othershapes of clamping members are possible. Members 42 and 43 may bespringy if desired.

Pads 40 and 4| and clamping members 42 and 43 with bolt 44 really form atransmission coupling with adjustable characteristics. Suitableapertures 45 in the casing give access to bolt 44 and permit adjustmentafter assembly. Flexible pads 46 and 41 at the center of the T may beprovided to engage the casing wall. Flexible pads 48 and 49 on oppositesides of the tail piece 21 may be also provided.

Clamping members 42 and 43 are adapted to clamp any vibratable elementof an energy translator between the head ends 50 and 5|. The meansclamped may be an armature of an electro-magnetic device, a piezocrystal, a condenser assembly or any other suitable means. Thus as shownin Figs. 1 and 2, a flat torsionally responsive crystal 52, suitablywrapped, may be gripped between clamping ends 50 and 5|. The crystal maybe braced at the faces and sides thereof by flexible pads 53' and 54.Wires 55 may be brought out to soldering terminals 56 carried byterminal block H.

The female clamp parts are more or less tightly coupled to thetranslator and both vibrate at an amplitude small in comparison to thatof the drive rod. Thus the effective inertia at the drive rod of therelatively massive female part of the coupling and the manual adjustmentis small.

In Figs. 6 and 7, a modification is shown where a condenser havingmovable plates is used as a translating device. In this form, aninsulating frame consisting of flat plates 60 and 6| with spacers 62 and63 is provided. Carried by plates 60 is a pair of metal electrodes 65and 66, these being long and narrow and preferably 'symmetrical withrespect to the longitudinal axis of plate 60. Plate. 6| also carriessimilar plates 6'! and 68. Spaced between these opposing electrodes is avibratable electrode plate 10 rigidly clamped at H and having formedintegral therewith clamps 'l2 and 13. Suitable insulating means such ashard rubber pads 15 may be provided at 12. Obviously plates 65 and-68 asone pair and 66 and 61 as the other pair cooperate with movable plate 10for translating action. A cross connected pair of three plate condensersis thus provided. Thus wire I! connects plates 65 and 68 and is broughtout to a terminal 18. Similarly wire I9 connects plates 66 and 67 and isbrought out to a terminal 80. Wire 8| is connected to movable plate 70.Thus push-pull circuit action is obtained. It is understood that wire 8|and one of the remaining two terminals inay be utilized in aconventional two wire sys- By virtue of the construction disclosedherein highly desirable characteristics are obtained. Thus thenon-circular journals at l8 and I9 provide increased elasticity to shockin the drive mounting perpendicular to the record. This would occur incase the entire device'were set down too hard on the needle. Guard 32 ofcourse protects the entire device against excessive shock. Also, theresilient mounting permits the needle to adjust itself in the recordgroove. By having substantial resiliency, groove wear in reproductionmay be greatly reduced.

The drive rod bearings also provide an end thrust protection and tend tohold the rod with some elasticity against longitudinal movement. Thisend thrust provision does not impair the rotational flexibility of themounting as is the case when the rubber supports are cemented to preventlongitudinal movement. The actual elastic structure is simplicityitselfmere1y some rubber tubing.

The provision of a simple fiat tail piece 21 and the clamp constructionalso has highly desirable features. Thus the drive rod is made simpleand light and has low rotational inertia. The clamp with its adjustingscrew is separated from the drive rod by flexible means here shown aspads 40 and M. Thus transmission characteristics between the drive rodand clamp may be controlled by pressure on the pads. The clamp andtranslating device are relatively tightly coupled. Because the clamp andbolt increase the rotational inertia of the vibratory system, it isdesirable to couple it closely to the translator. By controlling theclamp tension, the vibratory characteristics of the entire device may becontrolled within wide limits.

One highly desirable advantage of the construction is the readyremovability of a translating unit and replacement thereof. Thus anytranslating unit, crystal, electro-magnet or condenser, may be replacedwith another for any reason at all with a minimum of trouble.

It is clear that the assembly of the entire device may be accomplishedwith a minimum of equipment and skill. It is difficult to put anythingtogether incorrectly and after assembly, the adjustment on the clamp issimple.

What is claimed is:

1. In a phonograph translating device, the combination of a resilientlymounted torsion rod having a male coupling element at one end thereofand an energy translator having a vibratable element with a femalecoupling element, said rod normally vibrating over a greater amplituderange than said vibratable element, and resilient means between saidcoupling members, said coupling members being adapted to cooperate totransfer vibratory energy whereby efficient energy transfer is eifectedand th effective inertia of the system is kept low.

2. The system of claim 1 wherein said female coupling element has manualmeans for adjusting the degree of coupling between the couplingelements.

3. In a phonograph translating device, the combination of a resilientlymounted torsion rod having a flattened strip at one end thereof and anenergy translator having a vibratable element including spaced grippingmembers, said rod normally vibrating over a greater amplitude range thansaid vibratable element, said strip being adapted to extend between thespaced gripping members, and resilient means for controlling the degreeof coupling between said rod and gripping members whereby eflicientenergy transfer is effected and the effective inertia of the system iskept low.

4. The structure of claim 3 wherein a predominantly elastic means on oneside and a predominantly resistive means on the other side of said stripcomprise the resilient means.

5. The system of claim 3 wherein manual means are provided on thecoupling member for controlling the pressure of coupling exerted on saidtail piece.

6. In a phonograph translating device, a torsion rod having a flattenedtail piece, said rod being generally parallel to a record in the nor-.

mal position thereof, journals for supporting said rod, resilientsleeves between said rod and journals for biasing said rod to apredetermined torsional position, said resilient sleeves beingcompressed between said rod and Journal faces,.

means for varying the compression of said resilient means around saidrod to provide substantially more elasticity in a plane generallyperpendicular to a record and passing through the rod axis to permit therod to move in response to a lateral force, an energy translator havinga vibratable element, a pair of members embracing said tail piece andcan'ied by said vibratable element, resilient means between said pair ofelements and said tail piece for controlling the degree of coupling,said rod normally vibrating over a greater amplitude range than saidvibratable element.

7. The system of claim 6, wherein means are provided for ripping theends of at least one resilient sleeve around the rod at the journals forcontrolling end thrust.

8. In a. phonograph translating device, the combination of a resilientlymounted torsion rod having a flat tail piece at one end thereof, a

piezo-electric crystal of the torsional type, a

pair of coupling members extending between the crystal and tail pieceand embracing both on opposite sides thereof for transmitting torsionalvibration, and resilient means between said tail piece and couplingmembers for controlling the degree of coupling, said rod normallyvibrating over a greater amplitude range than said crystal.

9. The structure of claim 8 wherein manual means are provided forcontrolling the compression of said two members embracing the crystaland tail piece.

10. In a phonograph translating device, the combination of a resilientlymounted torsion rod having a flat tail piece at one end, a condenserassembly having one torsionally movable plate and stationary plates onopposite sides of said movable plate, said movable plate carrying a pairof coupling members embracing both sides of said flat tail piece, andresilient means between said tail piece and coupling members forcontrolling the degree of coupling, said rod normally vibrating over agreater amplitude range than said movable plate.

BENJAMIN B. BAUER.

